diff --git a/src/liballoc/arc.rs b/src/liballoc/arc.rs
index 74325afaebd48..b5d7279edb006 100644
--- a/src/liballoc/arc.rs
+++ b/src/liballoc/arc.rs
@@ -201,11 +201,12 @@ impl<T> Arc<T> {
         Arc { _ptr: unsafe { Shared::new(Box::into_raw(x)) } }
     }
 
-    /// Unwraps the contained value if the `Arc<T>` has only one strong reference.
-    /// This will succeed even if there are outstanding weak references.
+    /// Unwraps the contained value if the `Arc<T>` has exactly one strong reference.
     ///
     /// Otherwise, an `Err` is returned with the same `Arc<T>`.
     ///
+    /// This will succeed even if there are outstanding weak references.
+    ///
     /// # Examples
     ///
     /// ```
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 162312e2457da..dc283f5acdff8 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -224,11 +224,12 @@ impl<T> Rc<T> {
         }
     }
 
-    /// Unwraps the contained value if the `Rc<T>` has only one strong reference.
-    /// This will succeed even if there are outstanding weak references.
+    /// Unwraps the contained value if the `Rc<T>` has exactly one strong reference.
     ///
     /// Otherwise, an `Err` is returned with the same `Rc<T>`.
     ///
+    /// This will succeed even if there are outstanding weak references.
+    ///
     /// # Examples
     ///
     /// ```